The invention relates to a pot spinning device.
As in other spinning processes, the economy of the process in connection with centrifugal or pot spinning last but not least is a function of the required operating energy. In this connection it is known that a considerable portion of the expended operating energy is needed for overcoming the air friction occurring at the outer circumference of the spinning centrifuges in particular. This means that a large portion of the operating energy is converted into movement energy of the air surrounding the pot, which exhibits turbulent flow behavior at a number of revolutions of the spinning centrifuge of approximately 60,000 rpm.
Respective tests have shown that the required operating output increases, for example, with a power of three for the number of revolutions and with a power of four for the centrifuge diameter.
It was therefore already proposed in the past to have the spinning pot, which is also a name for the spinning centrifuge, run in as tight a spinning chamber as possible in order to reduce by this the air friction as a result of the turbulence.
A pot spinning device is known from German Patent Publication DE-AS 1 104 653, having a spinning pot rotating in a spinning chamber, wherein a rotatable intermediate housing is provided at a close distance between the spinning pot and the spinning chamber, and surrounds the greater portion of the spinning pot. The intermediate housing is rotatably seated by means of two rolling bearings and is taken along during the operation by the spinning pot, which rotates at a relatively high number of revolutions, so that the intermediate housing rotates at a lower number of revolutions than the spinning pot. This means that a difference in the number of revolutions is created between the intermediate housing and the stationary spinning chamber, which is clearly less than the number of revolutions of the driven spinning pot.
Since the air friction resistance occurring between the spinning pot and the intermediate housing, or respectively between the latter and the spinning chamber, remains comparatively low because of the clearly reduced differences in the number of revolutions, the drive output of the motor required for driving the spinning pot is reduced.
However, in connection with this known device it is disadvantageous that the spinning pot as well as the intermediate housing rotate in rolling bearings.
The frictional losses, which are unavoidable with rolling bearings, for example prevent the air friction occurring in the area of the rotating spinning pot from accelerating the intermediate housing to an optimal number of revolutions in regard to energy savings.
Moreover, limits have been set to rolling bearing technology in connection with pot spinning, last but not least because of the size of the required bearings, which is predetermined by the so-called characteristic number of revolutions value of these bearings. Here, the characteristic number of revolutions value is defined as the product of the number of revolutions in rpm and the diameter of the bearing in mm. The limits for such bearings primarily result from the large centrifugal force of the rolling bearings at the outer bearing ring, as well as the problematic lubrication of these bearings at high numbers of revolutions.
In connection with pot spinning it has also already been proposed to seat the spinning centrifuge in magnetic bearings.
German Patent Publication DE 42 08 039 A1 describes a pot spinning machine with spinning centrifuges seated in magnetic bearings.
In this known device the hollow-cylindrical spinning pots are kept suspended by the magnetic force. This means that magnetic bearings are provided at the respective ends of the spinning pots. Here, the magnetic bearings absorb the radial as well as the axial bearing forces. Moreover, sensors are provided in the area of the magnetic bearings for detecting radial deflections of the spinning pot. The results measured by these sensors are supplied to a position-regulating device assigned to the magnetic bearings, with the aid of which the position of the spinning pot can be stabilized.
A magnetic bearing for spinning centrifuges is also described in German Patent Publication DE 38 44 563 C.
In this known bearing, a permanent magnet gravity bearing is used for the machine element rotating at high speed, and a stabilizing bearing for the position regulation.